Add ComputerCraft fake player to bukkit.yml

This player is used by the ComputerCraft mod when turtles use
turtle.place(). Since ComputerCraft provides a username for this
player, this line is actually unnecessary, but adding it here
is useful for documentation purposes since an administrator
can easily edit this config option to change the name from the
default of "[ComputerCraft]", if needed.
Log fake player class name when first initialized

The EntityPlayer subclass provided by the mod for the
fake player is now logged, in addition to the username used,
for example:

 [FakePlayer] Initializing fake player for dan200/turtle/shared/TurtlePlayer: [ComputerCraft]

The class name is used for configuring the fake player in
bukkit.yml mcpc.fake-players, so it is logged here for reference.
Add login join events for mod fake players

Mod fake players can now optionally send Bukkit login and join
player events when they are first initialized. Off by default,
but some plugins may respond better to the fake players when
these events are enabled. Turn it on if you have problems.

As part of this change, the bukkit.yml mcpc.fake-players
configuration options were restructured.